feat(tooltip): use non-html tooltip when document is not defined

src/component/tooltip/TooltipModel.js

@@ -46,7 +46,10 @@ export default echarts.extendComponentModel({
 
         displayMode: 'single', // 'single' | 'multipleByCoordSys'
 
-        useHtml: true,
+        useHtml: 'auto', // 'auto', true, or false
+        // 'auto': use html by default, and use non-html if `document` is not defined
+        // true: use html for tooltip
+        // false: use canvas, svg, and etc. for tooltip
 
         // 位置 {Array} | {Function}
         // position: null

src/component/tooltip/TooltipView.js

@@ -51,7 +51,9 @@ export default echarts.extendComponentView({
         var tooltip = ecModel.get('tooltip');
 
         this._isRich = false;
-        if (tooltip.length && tooltip[0].useHtml === false) {
+        if (tooltip.length && (tooltip[0].useHtml === false // force using non-html
+            || tooltip[0].useHtml === 'auto' && !document)) // auto using non-html when no `document`
+        {
             this._isRich = true;
         }